From her biography, she was born in Ontario in the city of Mississauga. Her mother is a Filipina who is called Precious Garcia and her father is a Hispanic father who has also Scots-Irish origins and he is called Mark Mitchell. The parents are in the finance and the mother was born in Pampanga and went to Canada when she was 19 years old. She was born with a younger brother but he is too young and was born in the year 1996. Her second cousin niece is Lea Salonga who is a Tony Award winner actress and a singer. She was in the origination role as Miss Saigon of Kim.

Shay Mitchell got interested in the performing art when she was still young and she told her parents that she wished to follow that career. She started to learn how to dance when she was five years. When she was 10 years, the family decided to move to live in British Columbia in the city of West Vancouver. After a year, when they have reached there, she attended an open casting call for pre-teen and teens for international modeling agency. She was among the girls who were chosen. Shay Mitchell went to Rockridge Secondary School and afterwards, she transferred to live in West Vancouver Secondary School and this is the place where she finished.

In her late teens, Shay Mitchell was able to model for different companies in different cities including Barcelona, Hong Kong and Bangkok. Afterwards, she went back to learn acting Toronto. Her first role was when she signed up with the theatrical agency and she acted in Degrassi: The Next Generation. She booked different national commercials. She was a guest star of Global Series called Rookie Blue and he appeared in a music video called Hold My hand and it was by a Jamaican called Sean Paul. She was the cheerleader called Irina Webber of Aaron Stone of Disney XD.

Shay Mitchell appeared in the tv shows of ABC Family including Pretty Little Liars. At first, she was auditioning to play Spencer Hastings but she got a role of Emily Fields who played like a jock girl for a group. The movie is about a group of four people and they were to fight against an enemy that threatened to reveal all their secrets. Even if she does not like to talk about her personal life, everything she does shows that her boyfriend is Ryan Silverstein. For her weight, she is 60kg and her height is 1.71m. Her body measurement is 37-25-34.